U.S. patent number 9,732,766 [Application Number 14/226,309] was granted by the patent office on 2017-08-15 for electric motor-driven compressor having a heat shield forming a wall of a diffuser.
This patent grant is currently assigned to Honeywell International Inc.. The grantee listed for this patent is Honeywell International Inc.. Invention is credited to Patrick Beresewicz, Mike Guidry, Rick Johnson, John Mason, Glenn F. Thompson.
United States Patent |
9,732,766 |
Thompson , et al. |
August 15, 2017 |
Electric motor-driven compressor having a heat shield forming a
wall of a diffuser
Abstract
An electric motor-driven compressor includes a housing assembly
comprising a motor housing and a compressor housing mounted
thereto. The compressor housing contains a centrifugal compressor
wheel that is mounted on a shaft of the motor rotor and also
defines an air inlet that leads air into the compressor wheel, and
a volute that collects the compressed air. Air bearings rotatably
support the shaft. Cooling air passages are defined in the housing
assembly for supplying cooling air to the air bearings. A diffuser
between the exit of the compressor wheel and the volute serves to
diffuse the compressed air. The compressor includes a heat shield
formed separately from the compressor housing and the motor housing
and disposed between them. The heat shield defines one wall of the
diffuser and also cooperates with the housing assembly to define
part of the cooling air passages for the cooling air supplied to
the bearings.
Inventors: |
Thompson; Glenn F. (Palos
Verdes Estates, CA), Guidry; Mike (Redondo Beach, CA),
Mason; John (Torrance, CA), Johnson; Rick (Torrance,
CA), Beresewicz; Patrick (La Mirada, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Honeywell International Inc. |
Morristown |
NJ |
US |
|
|
Assignee: |
Honeywell International Inc.
(Morris Plains, NJ)
|
Family
ID: |
52807532 |
Appl.
No.: |
14/226,309 |
Filed: |
March 26, 2014 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20150275920 A1 |
Oct 1, 2015 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04D
17/125 (20130101); F04D 29/584 (20130101); F04D
29/5853 (20130101); F04C 29/047 (20130101); F04D
25/0606 (20130101); F04D 29/102 (20130101); F04D
29/057 (20130101); F04D 29/5806 (20130101); F04D
29/0513 (20130101); F04D 29/5846 (20130101); F04D
29/056 (20130101); F04D 25/06 (20130101); F04D
17/12 (20130101) |
Current International
Class: |
F04D
29/58 (20060101); F04D 29/056 (20060101); F04D
25/06 (20060101); F04D 17/12 (20060101); F04C
29/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1479335 |
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Nov 2004 |
|
EP |
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2335710 |
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Sep 1999 |
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GB |
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2427248 |
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Dec 2006 |
|
GB |
|
Other References
US. Appl. No. 14/184,122, filed Feb. 19, 2014, In re: Thompson et
al., entitled Sealing Arrangement for Fuel Cell Compressor. cited
by applicant .
U.S. Appl. No. 14/265,664, filed Apr. 30, 2014, In re: Thompson et
al., entitled Electric Motor-Driven Compressor Having an Electrical
Terminal Block Assembly. cited by applicant .
U.S. Appl. No. 14/264,677, filed Apr. 29, 2014, In re: Thompson et
al., entitled Electric Motor-Driven Compressor Having B-Directional
Liquid Coolant Passage. cited by applicant .
EPO Search and Opinion for Appl. No. EP 15158472.9, dated Sep. 24,
2015. cited by applicant.
|
Primary Examiner: Freay; Charles
Assistant Examiner: Hansen; Kenneth J
Attorney, Agent or Firm: James; John C.
Claims
What is claimed is:
1. An electric motor-driven compressor comprising: a housing
assembly comprising a motor housing and a first compressor housing
mounted to one end of the motor housing, the motor housing
containing a motor stator and a motor rotor having a shaft, the
motor housing defining a bore through which the motor rotor and the
shaft pass; the first compressor housing containing a first
centrifugal compressor wheel that is mounted on one end of the
shaft for rotation therewith, the first compressor housing also
defining a first compressor flow path including a first air inlet
that leads air into the first compressor wheel, and a first volute
that collects compressed air that has passed through and been
compressed by the first compressor wheel; a second compressor
housing mounted to an opposite end of the motor housing and a
second centrifugal compressor wheel contained in the second
compressor housing and affixed to an opposite end of the shaft, the
second compressor housing defining a second compressor flow path
including a second air inlet that leads air into the second
compressor wheel, and a second volute that collects compressed air
that has passed through and been compressed by the second
compressor wheel, and further comprising an interstage duct that
connects the second volute to the first air inlet such that air
compressed by the second compressor wheel is led by the interstage
duct from the second volute into the first air inlet and is further
compressed by the first compressor wheel and delivered into the
first volute; a first diffuser between an exit of the first
compressor wheel and the first volute, the first diffuser serving
to diffuse the compressed air to a lower velocity and deliver the
compressed air into the first volute; air bearings disposed in the
motor housing and rotatably supporting the shaft; cooling air
passages defined in the housing assembly for supplying cooling air
to the air bearings; a heat shield that is formed separately from
the first compressor housing and the motor housing and is disposed
therebetween, the heat shield defining a mounting flange located at
a radially outer periphery of the heat shield, and defining a
shield portion that extends radially inwardly from the mounting
flange and forms one wall of the first diffuser for the compressed
air delivered into the first volute, the heat shield also
cooperating with the housing assembly to define part of the cooling
air passages for the cooling air supplied to the air bearings;
wherein the mounting flange of the heat shield is captured between
a first compressor housing portion and a motor housing portion such
that an annular space is bounded by the mounting flange at a
radially outer side of the annular space and by the shield portion
and the motor housing on opposite axial sides of the annular space,
said annular space being located proximate the first volute for
receiving cooling air; wherein the motor housing defines a cooling
air inlet that receives a portion of air from the second volute,
and defines a passage that supplies part of said portion of air
into the annular space proximate the first volute; and wherein the
mounting flange of the heat shield engages the motor housing to
space the shield portion of the heat shield axially away from a
face of the motor housing so as to form a cooling air gap between
the shield portion of the heat shield and said face of the motor
housing, the cooling air gap being connected to the annular space
and extending radially inwardly therefrom and being supercharged by
cooling air from the annular space, and wherein a radially
innermost part of the shield portion engages said face of the motor
housing to close off the cooling air gap at a radially inner end
thereof to make the cooling air gap deadheaded.
2. The electric motor-driven compressor of claim 1, wherein the
motor housing defines a liquid coolant passage for circulating a
liquid coolant, the mounting flange of the heat shield being in
contact with the motor housing cooled by the liquid coolant so as
to facilitate heat transfer from the mounting flange to of the
motor housing.
3. The electric motor-driven compressor of claim 1, further
comprising a first seal carrier affixed to the shaft intermediate
the first compressor wheel and the air bearings, and a first seal
ring engaged in a circumferential groove formed about the first
seal carrier, and wherein the first seal ring is positioned to seal
against a radially inner surface of the heat shield so as to
discourage air leakage between the first compressor flow path and
the air bearings.
4. The electric motor-driven compressor of claim 3, further
comprising a second seal ring engaged in a second circumferential
groove formed about the first seal carrier and positioned to seal
against the radially inner surface of the heat shield.
5. The electric motor-driven compressor of claim 1, wherein the
cooling air passages are arranged for receiving cooling air from
the annular space.
6. The electric motor-driven compressor of claim 1, wherein the
housing assembly defines an annulus adjacent the second compressor
wheel, the annulus receiving cooling air from the cooling air
inlet, and wherein said passage defined in the motor
housing-comprises an axially extending conduit for feeding cooling
air from said annulus into the annular space defined between the
heat shield and the motor housing.
Description
CROSS-REFERENCE TO RELATED APPLICATION
The present application is related to commonly owned, co-pending
Application Ser. No. 14/184,122 filed on Feb. 19, 2014, the entire
disclosure of which is hereby incorporated herein by reference.
BACKGROUND
The present disclosure relates to electric motor-driven compressors
such as used for fuel cells.
Air compressors can be used to increase the efficiency of a fuel
cell by providing compressed air to the cathode side of the fuel
cell. A two-stage compressor may be used in some applications
requiring a higher pressure than achievable in a single compressor
stage. In a two-stage compressor, a low-pressure compressor wheel
is provided on a shaft, and a high-pressure compressor wheel is
provided on the same shaft. The shaft is driven by an electric
motor so that the compressor wheels are rotated, and air enters the
low-pressure compressor wheel and is compressed to a first
pressure. The compressed air is then passed on to the high-pressure
wheel for a further increase in pressure. The air from the
high-pressure compressor wheel is then delivered to the fuel cell
to promote the fuel cell reaction.
The electric motor used in a compressor for a fuel cell is
typically a high-speed, high-output motor that generates a
significant amount of heat. It is generally desirable to minimize
the heat transfer between the motor and the air being compressed in
the compressor, and the heat transfer between the motor and the
bearings for the compressor shaft.
BRIEF SUMMARY OF THE DISCLOSURE
The present disclosure describes embodiments of electric
motor-driven compressors such as useful with fuel cells or in other
applications. In one embodiment, for example, an electric
motor-driven compressor includes a housing assembly comprising a
motor housing and a compressor housing mounted to the motor
housing. The motor housing contains a motor stator and a motor
rotor, and defines a bore through which a rotatable shaft passes.
The compressor housing contains a centrifugal compressor wheel that
is mounted on the shaft for rotation about the shaft axis. The
compressor housing also defines an air inlet that leads air into
the compressor wheel, and a volute that collects compressed air
that has passed through the compressor wheel. A diffuser between
the exit of the compressor wheel and the volute serves to diffuse
the compressed air to a lower velocity and consequently a higher
static pressure.
The electric motor-driven compressor in one embodiment includes air
bearings that rotatably support the shaft. Cooling air passages are
defined in the housing assembly for supplying cooling air to the
air bearings.
In accordance with the present disclosure, the electric
motor-driven compressor includes a heat shield that is formed
separately from the compressor housing and the motor housing and is
disposed between them. The heat shield defines one wall of the
diffuser for the compressed air delivered into the volute. The heat
shield also cooperates with the housing assembly to define part of
the cooling air passages for the cooling air supplied to the air
bearings.
In one embodiment, the motor housing defines a liquid coolant
passage for circulating a liquid coolant, and the heat shield
defines a mounting flange captured between the motor housing and
the first compressor housing. The mounting flange is in contact
with a portion of the motor housing cooled by the liquid coolant so
as to facilitate heat transfer from the mounting flange to said
portion of the motor housing.
In one embodiment, the heat shield and the motor housing are
arranged so as to define an annular space therebetween for
receiving cooling air, and the cooling air passages are arranged
for receiving cooling air from the annular space. A cooling air gap
additionally can be defined between the heat shield and the motor
housing, the cooling air gap being arranged to receive cooling air
from the annular space.
The compressor can also include a first seal carrier affixed to the
shaft intermediate the first compressor wheel and the air bearings,
and a first seal ring engaged in a circumferential groove formed
about the first seal carrier. The first seal ring is positioned to
seal against a radially inner surface of the heat shield so as to
discourage air leakage between the first compressor flow path and
the air bearings.
The features of the present invention can be applied to a two-stage
serial compressor, such as the embodiment illustrated and described
herein. In the case of such a two-stage compressor, a second
compressor housing is mounted to an opposite end of the motor
housing and a second centrifugal compressor wheel is contained in
the second compressor housing and is affixed to an opposite end of
the shaft. The second compressor housing defines a second
compressor flow path including a second air inlet that leads air
into the second compressor wheel, and a second volute that collects
compressed air that has passed through and been compressed by the
second compressor wheel. An interstage duct connects the second
volute to the first air inlet such that air compressed by the
second compressor wheel is led by the interstage duct from the
second volute into the first air inlet and is further compressed by
the first compressor wheel and delivered into the first volute. The
second compressor wheel thus constitutes a low-pressure compressor
wheel and the first compressor wheel constitutes a high-pressure
compressor wheel.
In the two-stage compressor embodiment, the heat shield and the
motor housing are arranged so as to define an annular space
therebetween for receiving cooling air, and the cooling air
passages are arranged for receiving cooling air from the annular
space. The motor housing defines a cooling air inlet for supplying
the cooling air that is received in the annular space. The housing
assembly can define an annulus adjacent the low-pressure compressor
wheel, the annulus receiving cooling air from the cooling air
inlet, and the motor housing can define an axially extending
conduit for feeding cooling air from said annulus into the annular
space defined between the heat shield and the motor housing.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
Having thus described the present disclosure in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale, and wherein:
FIG. 1 is a side view, partly in section, of an electric
motor-driven compressor in accordance with one embodiment of the
invention, comprising a two-stage compressor having a low-pressure
compressor and a high-pressure compressor in series;
FIG. 2 is a magnified view of a portion of FIG. 1, showing details
of how cooling air is supplied into an annular space between the
heat shield and the motor housing; and
FIG. 3 is a magnified view of a portion of FIG. 1, showing details
of the heat shield and its arrangement in the high-pressure
compressor.
DETAILED DESCRIPTION OF THE DRAWINGS
The present invention now will be described more fully hereinafter
with reference to the accompanying drawings in which some but not
all embodiments of the invention are shown. Indeed, aspects of the
invention may be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein; rather,
these embodiments are provided so that this disclosure will satisfy
applicable legal requirements. Like numbers refer to like elements
throughout.
The present invention may be applied in a variety of types of
electric motor-driven compressors, including single-stage as well
as multi-stage electric motor-driven compressors. The particular
embodiment described herein for purposes of explaining the
principles of the invention is a serial two-stage compressor having
two centrifugal compressors arranged in series, but the invention
is applicable to parallel two-stage compressors as well as other
types. Thus, a simplified cross-sectional view of a serial
two-stage electric motor-driven compressor 10 for use with a fuel
cell (such as a proton exchange membrane (PEM) fuel cell) is shown
in FIG. 1. The two-stage compressor 10 includes a housing assembly
comprising a motor housing 20, a low-pressure compressor housing 40
mounted to one end of the motor housing, and a high-pressure
compressor housing 60 mounted to the other end of the motor
housing. The motor housing 20 contains a motor stator 22 and a
motor rotor 24 having a shaft 26 about which permanent magnets 28
are fixedly mounted. The motor housing 20 defines a bore 30 through
which the motor rotor 24 and the shaft 26 pass. Air bearings 32 are
disposed in the motor housing 20 for rotatably supporting the rotor
24 and shaft 26.
The low-pressure compressor housing 40 contains a centrifugal
low-pressure compressor wheel 42 that is mounted on one end of the
shaft 26 for rotation therewith, the low-pressure compressor
housing also defining a low-pressure compressor flow path including
an air inlet 44 that leads air into the low-pressure compressor
wheel, and a low-pressure volute 46 that collects compressed air
that has passed through and been compressed by the low-pressure
compressor wheel. The low-pressure compressor also includes a
diffuser 45 that leads the compressed air from the low-pressure
compressor wheel 42 into the low-pressure volute 46, and serves to
reduce the velocity and increase the static pressure of the air
going into the volute.
The high-pressure compressor housing 60 contains a centrifugal
high-pressure compressor wheel 62 that is mounted on the opposite
end of the shaft 26 for rotation therewith. The high-pressure
compressor housing defines a high-pressure compressor flow path
including an air inlet 64 that leads air into the high-pressure
compressor wheel, and a high-pressure volute 66 that collects
compressed air that has passed through and been compressed by the
high-pressure compressor wheel. The high-pressure compressor also
includes a diffuser 65 that leads the compressed air from the
high-pressure compressor wheel 62 into the high-pressure volute 66,
and serves to reduce the velocity and increase the static pressure
of the air going into the volute.
The compressor further includes an interstage duct 50 that is
connected between the low-pressure volute 46 and the inlet 64 to
the high-pressure compressor for routing the compressed air from
the low-pressure volute 46 to the high-pressure compressor for
further pressurizing in a second-stage compression process.
Cooling air passages are defined in the housing assembly for
supplying cooling air to the air bearings 32. In particular, with
reference to FIG. 2, cooling air is supplied into a cooling air
supply inlet 70 defined in the motor housing 20. For example, in
the case of the compressor 10 being used in a fuel cell system for
a vehicle, where the compressed air from the high-pressure volute
66 is passed through a vehicle heat exchanger to cool the air
before it is supplied to the fuel cell, a portion of the air
exiting the heat exchanger can be tapped off and supplied into the
cooling air supply inlet 70. From there, the cooling air passes
into an annulus 72 defined cooperatively by the motor housing 20
and low-pressure compressor housing 40. A portion of the cooling
air in the annulus 72 is directed radially inwardly through passage
73 and is fed to both sides of a thrust plate 43 for the
low-pressure side air thrust bearing. The air on the inboard
(motor) side of the thrust plate 43 feeds the journal air bearing
32 (also cooling the rotor magnet 28) and is then discharged into
the motor cavity. The air on the outboard side of the thrust plate
43 proceeds radially outwardly through passages 47 into an annular
space 49 defined in the compressor housing, and from there it
proceeds through a passage 51 into the motor cavity.
The remainder of the cooling air in the annulus 72 is directed
through an axially extending cooling air conduit 74 that extends
from the annulus 72 through the motor housing 20 and connects with
a further annulus 76 (FIGS. 1 and 3) in the region of the
high-pressure compressor. With reference to FIG. 3, the motor
housing 20 defines cooling air passages 78 that lead from the
annulus 76 generally radially inwardly into a generally annular
space 80 at the high-pressure end of the motor rotor 24. Cooling
air fed into the generally annular space 80 passes generally
axially (to the left in FIG. 3) and feeds the journal air bearing
32 for the rotor 24 (also cooling the rotor magnet 28) and is then
discharged into the motor cavity.
The cooling air in the motor cavity is evacuated from the motor
cavity via a port 71, which is connected via a conduit 71a to a
housing discharge port 71b (FIG. 1).
With reference now to FIG. 3, the high-pressure compressor includes
a generally annular heat shield 100 that is formed separately from
the high-pressure compressor housing 60 and the motor housing 20
and is disposed therebetween. In particular, the heat shield 100
has a flange 102 at its radially outer periphery, and the flange
102 is disposed, with respect to the radial direction, between a
flange 68 of the compressor housing 60 and a shoulder 21 of the
motor housing 20, and is sandwiched between the flange 68 and
shoulder 21 so as to constrain the heat shield radially. The heat
shield flange 102 is captured and constrained axially between a
motor housing flange 23 and a shoulder 67 on the HP compressor
housing 60. A V-band clamp 35 clamps together the motor housing
flange 23 and HP compressor housing flange 68, and a sealing ring
69 disposed between the HP compressor housing shoulder 67 and the
heat shield flange 102 is thereby axially compressed between these
parts, thereby sealing the interface between the heat shield and
the compressor housing. The heat shield 100 includes a radially
directed wall portion 104 that extends radially inwardly from the
flange 102 and defines one wall of the diffuser 65 for the
compressed air delivered into the HP volute 66, an opposite wall of
the diffuser being defined by the HP compressor housing 60.
With continued reference to FIG. 3, the previously described
cooling air annulus 76 is defined cooperatively by the heat shield
100 and the motor housing 20. The cooling air passages 78 in the
motor housing extend from the annulus 76 radially inwardly and feed
the cooling air into the space 80 from which the air feeds the
journal bearing as previously described. Thus, the heat shield 100
cooperates with the housing assembly to define part of the cooling
air passages for the cooling air supplied to the air bearings.
The heat shield 100 also helps minimize heat transfer from the hot
motor housing 20 to the air passing through the high-pressure
compressor. To this end, the motor housing 20 makes little contact
with the heat shield 100. The motor housing 20 defines a liquid
coolant passage 25 for circulating a liquid coolant through the
housing around the stator 22. The heat shield's mounting flange 102
captured between the motor housing 20 and the HP compressor housing
60 is in contact with a portion of the motor housing cooled by the
liquid coolant in the liquid coolant passage 25 (note the close
proximity of the flange 102 to the coolant passage 25 in FIG. 3) so
as to facilitate heat transfer from the mounting flange to said
portion of the motor housing. There is also an air gap 77 between
the heat shield 100 and the motor housing 20. Air from the annulus
76 supercharges this dead-headed air gap 77. All of these features
contribute toward the minimization of heat transfer from the motor
housing, via the heat shield, to the air being compressed in the HP
compressor.
The heat shield 100 additionally serves yet another function,
namely, providing a sealing surface for the seals that
substantially isolate the HP compressor discharge air from the HP
journal bearing. Thus, the compressor includes a seal carrier 63
affixed about the shaft 26 at a location intermediate the HP
compressor wheel 62 and the air journal bearing 32. A seal ring 63a
is engaged in a circumferential groove formed about the seal
carrier 63, and the seal ring is positioned to seal against a
radially inner surface of the heat shield 100 (FIG. 3) so as to
discourage air leakage from the HP compressor flow path into the
journal air bearings. In the illustrated embodiment, there is also
a second seal ring 63b in a second groove in the seal carrier 63 to
further enhance the sealing.
While the invention has been described by reference to an electric
motor-driven two-stage serial compressor, the invention may also be
applied to other electric motor-driven compressors, such as a
single-stage compressor. In the appended claims, references to a
"first compressor wheel" are to be understood as applying either to
the HP compressor wheel of a two-stage serial compressor (in which
case the "second compressor wheel" is the LP compressor wheel), or
to a compressor wheel in a single-stage compressor.
Many modifications and other embodiments of the inventions set
forth herein will come to mind to one skilled in the art to which
these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the inventions are
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Although specific terms
are employed herein, they are used in a generic and descriptive
sense only and not for purposes of limitation.
* * * * *